The importance of phase-encoding order in ultra-short TR snapshot MR imaging.

We show the importance of phase-encoding order in ultra-short TR (less than 10 ms) snapshot MR imaging. Contrast is more heavily dictated by the contrast preparation phase early in the measurement phase than later. When the low spatial frequencies are measured first, the resultant image contrast more closely resembles that established by the preparation phase. The transient nature of the data acquisition causes a kappa-space filter to be applied to the data. The effects of this filter can be minimized by appropriate choice of scan parameters.